Project Summary We propose to acquire a machine that performs serial two-photon tomography of fluorescent cells in whole organs. The machine, a TissueCyte 1000 Imaging Platform manufactured by TissueVision, is an automated system that serially sections and images whole tissues, and will allow users to create anatomical datasets of brains and other organs automatically. The technology has been transformative for neurobiology research as it allows unbiased analysis of fluorescence throughout the entire brain. This enables comparisons of anatomical tracts across experiments, genotypes, and conditions. Furthermore, it greatly improves experimental rigor and systematic discovery as it eliminates the many user-dependent steps typical to other fluorescence imaging modalities. Lastly, it provides data in a format that has been extensively validated, for which automated analysis routines exist, and in which the hosting community has extensive experience. The P30 Neurobiology Imaging Facility at Harvard Medical School/Boston Children's Hospital (HMS/BCH; NINDS P30 NS072030) will house the equipment, provide technical expertise to the entire neuroscience community, and continue to create an opportunity for collaborations across laboratories and institutions. This technology will catalyze research at HMS/BCH focusing on nervous system disorders by facilitating a systematic comparison of three-dimensional anatomical tracts in animal models of nervous disease and interrogate the circuit basis for neurological diseases.